Attachment for surveying instrument.



PATENTE!) MAR. 27, 1906.

No, 8l6,422.

W. M. BEAMAN. ATTACHMENT FOR SURVEYING INSTRUMENTS.

APYLIGTBH FILED JUNE 14.1905.

(Hf l wituaoa (92). K f7 ATTACHMENT FOR SURVEYING NSTHUMENTS.

Specification of Lettera Patent.

Yatented Maren 2*?, 1906.

Application filed June l, 1905. Serial Re. 265.185.

To nl! wirmt it nung; ermee-ru:

Be it known that l, WILMAM lll. BEAMAN, e citizen of the United States, residing at lVashingtou, in the District oi Columl'iis,

have inventeda new and useful Attaclnnent for Surveying Instrument-s, of which the foi lowing is a specification.

This invention relates to ssrseying instroments carrying s vertical are sind stsdisf Wires, and more particularly to 'these intended for determining differences in elevation and reduced distances between the instruS ment and e stadia-rod.

The object of' my invention is to 'provide an attachment for a surveying instrument whereby differences m elevation een be quickly and accurately determined without either' theJ measurement oi an angle, the use of a `Vernier, the useJ of a table or chart, and with only very slight computation.

'ect of this invention is te pron Another olii vide an attac meent by means of Widen not only the differences in elevation are determined, but also the true distance reduced to horizontal with the same ease end'accurecy as before referred to; dnd a. still iurther ob- `ect is to provide an attachment which een e used in connection with any of the wellknown forms ol survein instruments and one which can be attac cdgto the vertical ere or which can be made to replace said vertieel are.

With these objects in viiew my invention consists, broadly, in the employment of en are graduated according to a` law Vof naturel eines, said are being movable with the tele scope, and en adjustable index adopted for use in connection with the graduated are, but movable independent thereof. i'

The inventionoonsists also in the einploy- Y ment of en are graduatedV according te s law Y of naturel eosines and arranged beside the src graduatedaceording to a law of natural eines and en adjustable index common toxhetli graduated ares. Y' ,i

The invention consists also in certain dse tails of construction hereinafter fully de'- scribed, :md pointed out ,in the claims. 1

.1n the drawings forming s part of this speoilioetion, Fi re l is a pers estive View of a surveyinv-te escupe reside with my ettecliment. ig. 2 is s etail sideelevation. Fig. 3 is a. detail to alan view, and Fig. 4 is an enlarged view o tile scales and adjustable index. l

Referring to the drawings, A indicates a .13, supporting the ordinary Isles-eo )e of the usual or any` a qnoved'type, seid teleszro e being supported upon s l1orizontal exis resting on standards C, one of `which is extended horizontsiiy, es shown at l', This extension or arm ordinarily serves o support for the Vernier; but l also em- Y pioy it es a point el atteelnm-znt for the adjust able index-plate hereinafter reierred to.

Rigidly attached to the asis B are the arms graduated are E, to which are secured the eres l? and G. It will be understood that the are E is not used in my method and is not at all essential to my invention. The graduated arcs F and G met' be made in e single piece or separately and attached to the ends of the arms D. Another erm H is hinged loosely on the axis B end carries et its outer end a plate cerrjfing the indexdine J. This late l is slotted vertically, as shown at I', t irough which screws li pass into the end of the extension C tend over. next to the graduated seele F, as most clearly shown in Figs. 1, 3, and 4. The arm HV has a depending. finger H', against which bears en adjusting-screw E., working tl u'ou gh the standards C, ed a spring-pressed rod L olds the linger always in contact with the end of the screw, so that by adjusting.tlie screw the plate I can bemoved uli or down for the purpose of raising or lowering the indexline J It will be understood that the movement of the index-plate l is dependent entirely upon the screw K and is independent of any niojrernent of telesco e and eres.

In looking tlirougli s telescope fitted with fixed stadia-wires and et a, sertieel stadiai'od whose face is divided into an number of equal divisions We see the sta ia-wires projected upon the rod. The theory of the measurement of distances by the stadia method is that the space subtended on the i rod byth'ese wires is exaetiy proportional to the distance of the rod from the telesoo e.

It is enstomary to divide the sta iai-rod into units of some convenient length and fractions thereof and then to set the stadiawires ut snob a. iixed distance apart that whenY one unit is subtended by them on the rod the rod is one hundred units in distance from the telescope. New if the line of sight is horizontal the observed stadia. distance is the true distance, (certain minor corrections are here ignored but if this line is inclined to TheV lower end oi the plate l, ss fhicli carries the index-line J, is made suiieiently broad to eir-Y rio the horizontal we can computo the dillerence :n elm atimzfronz the .iutaobsc1ved distance, and measured vertical angle by welldznown foi-unibe. 'lo facilitate these operations, various tables, charts, diagrams, and slidcwulcs have in the past been devised. They all involvo the measurement of a vertical angle, in-

cluding the reading of' a Vernier, the entering of a table or diagram, and the "subsequent performance of either a tiresome computation or thc acceptance ofonly an approximate result, due to an awkward interpolation.

Brieii 'stated my invention is used as follows: t is assumed that the observed distance has been read in the usual manner and that the rod has been held vertically.) -Whcn telescope is level, an adjustable index is set at thel zoro-point of a new-vertical-arc scale. When the telescope is turned toward the rod, (the new arc carrying F and G moving rigidly with it, while the index-J remains stationm3,) I do not make au exact settin v at any definite point on the rod, but instea set the nearest arc-graduation exactly op osite the index and then note the arc and ro readuigs.

There are two independent scales side ,bv side on the same face o next thc index-(always small and Whole and never fractional) are so placed Vin angular value that when that number indicated by the scale-rc ad ing is multiplied by theobserved distance, expressed in Subtended unitsfit gives the exact difference in elevation be tweel': the instmn'i-ent and that point on the rod which is. mywhehind the middle Wire. Second, if it is desirable to reduce the bserrwl distance to true horizontal distance, then apply such correction to it as is indicated by the reading of the reduction-scale G opposite the same lndex J lust used.l The correction is expressed on t .c scale in percentage to be subtracted, from observed dis tance, each subtended unit on rod being ,here regarded as re rescnting one hundred units of'distancc.' bale F is for determining differences in' elevation. The zero-pointis marked instead of 0, so that the scale asrfd (always an even division and never estimated between) will show and the notes will afterward prove the sign ci the angular value re resented. The graduations run outward 1n either direction from the zeropointor the 50 graduation and for the saine number of vdivisions on either side from "50 are graduatedat eoualdistanccs from Also if' the line of si ht is hori-A the new verieal'arc.l First, the numbers on the elevation-scale F said zero-point. The numbering here from about "1(), which represents a minus angular value' of 26 33.9', to about 96,, winch rc resents a plus an ular value .of 26 33.9. he scale is read in t e usual way-8.3, e. g., 54, 62, 47, 85e. The angular range as here shown could be made less or greater, or ufdif'lerent zero-numeral than 50 could obviously be used without departing from the spirit of my invention.

'lhe graduations follow a law of natural sines and are computed from the formula /L 1- S sine 2 a, (based on vertical rod,)

where 7L equals difference in elevation, s equals observed stadia distance` a equals vertical anglo or inclination of the telescope to the horizontal.

Now in ,order that the various point-ings of the telesco e on the rod shallgive whole-num ber multip es rangin from one to forty plus, and sirnilarl f one to crty minus, which when multiplied y the Observed stadia distance (units on rod subtendedbetween the fixed stadia-wires) willgive at once the difference in elevation, forty corn utations have been made with the above ormula, as follows: Such angular values have been found as Will make i sine 2 a 1, 2, 3, &c., respectively-e. 95 g., when a equals 5 46.1 sine 2 a (L1-but as the observed stadia distance is usually read as so many units subtended on rod this is multiplied byone hundred to get actual distance, so we multiply above result by one roo hundred, thus 0.1 100 :1074, e., when telescope is inclined 5 46.1 to horizontal the are reading 'is 10, (60- 50= 10,) which means that ten times the numbers of units subtended on 'the rod between the stadia- 105 `Wires is the difference in elevation, subject to iinal correction for height on rod sighted.

Therefore to` get themultiple to be used in tbe computation I subtract fifty from thearc setting as read, and the algebraic result is the 1 xo multiple with appropriate sign. Thus 54- in the angular value cited above 5 46.1,

which gives a multiple of ten, the tenth graduation above 50" and the tenth graduation I 15 below 50 are each placed 5 46.1 in angular distance on either side of the zero-point,

but are marked 60' and 40 respectively.

It is thus that the reading of a Vernier and the consequent determination of `a vertical les angle is made unnecessary, for the reason,

that the fractional part of a division, ap arentv necessary, but really to .be avoide ,is

rea as so man units of height on the' rod, as

indicated by t c height of the middle Wire 12F (stadia-wiresbeing disregarded) counting up from the round as zero. l'

Scale is for dcterminin correction necessur'y toreduceobserved stance to .horil:rental on account of.,line of sight beinlglinscale G.

clined to horizontal. The zero- @int is marked 0" and is exactl yo osito t e 50" (or zero-point) of seele n seais G the graduations are numbered consecutively and outwardly from 0 in eithcrrrdirection (up and down) and are placed in such angular positions as will indicate even percentages of correction. The same index is used to read both scales. When telescope is finally set with the rod in the lield of view and Index fellin exectly opposite some radnnticn of scale as prcvicuslyexpiaine l then note the readin of the index by estimation on f nearest reading, e. g., is 4,

then reduce observed distance l) four per lcent. For a more exact value, if esired,the'

nearest tenth of a per cent. een be easily read i by estimation. of tenths.

The graduations follow a law of natural cosines, and the angular position for each graduation is computed from the formula d=s cos c, V(based on verticel rod,)

where d equals true horizontal distance, s equals observed stadia distance, c equals ver tical angle or inclination of telescope to the horizontal.

To facilitate the sli ht computation necessary in determining ifferences in elevation, I have devised s. special form of notes, which follow the general form of those used in dif ierential leveling.v The following will serve as a. sample:

Undercolumn of istoncs, 7.3, 6.7, and 4.8 are units subtended on rod by stadia-wires and represent seven hundred and thirt sin hundred and seventy, and four hun red and eighty units of distance, respectively. Under column of Rod and product, 8.4, 7.1, and 9.2 are units on rod between its base and middle wire-Ji. e.l the nal rod readings-wlien are reading 1s teken. A complete note entr for the first backsight wiiicli means that 6 X 7.3 43.8 is l). E. between instrument and that point on rnd which is 8.4 above groundi The proper signs for final rod readings and for products are V' Take rod readings and products by pairs and add al l'cbrn.ically, e. 8.4; 8.8== 35.4, whic i np lied aigeiiraionily to start in -point i001) gives 64.6. f

t is to be noted that in mostsu rveying instruments the vertical arc is placed on the side of the telesco' e, where the l'raduations are on a scale whio i is in a vertice. plane parallel to then telescope. In the drawings here= with, however, the graduations are on the side of the nrc facing the eyepiece of the teli; scope, simply for convenience in reading.

My invention is es attaoliable in the one osition as in the other, the only difierences eing in the mechanical arrangements of the various arts.

In cit ier case the principles involved and the methods of use es above described n'nrl the elainis made below nre ol' identical application. r

Having thus fully described my invention, what Icleim as new, and desire to secure by Letters Patent, is* A l.Y In a surveying instrument, a telescope provided with stadia-wires, and an ero conneetedto the telescope end movable therewith and a movablevindex arranged in oombination with the said telescope und are, said are being graduated according Yto a law of naturel eines, whereby a singin reading of the i `instrument used in connection with a stadia- Vrod will be suicient to determine the difierenoe in elevation between the instrument and rod` tion with the telescope having an ordinary nrc connected thereto and movable therewith, of a supplemental arc, connected to the inst-mentioned are, said supplemental arc being graduated according to a law of natural eines, and an index movable independent of tbe tele-scope, said index extending across the first-mentioned arc and resting against the su plernentsl arc fertile purpose specied. 3. iii a surveying instrument a telescope iiaving en ordinary arc, a supplemental are, having graduations adjacent oth edges, one set cf graduations being according to o lew of naturel eines, and the other set of graduations being according to a law of natural co eines, and a movsbleindex extend-ingacross the ordinary are and resting Rush with the supplemental are for the purpose specified.

4. a vertical arc and a. movable index, said are being graduated outwardly from a zero-point 2. In s. surveying instrument the combina- In a surveying instrument, n telescope, j

neer its middle and similarly on either side of sind zero-punit, seid ruduutions follow1nr n certain law of natura eines, seid ure having rod, whereby further emnputatinn is avoided, l

es described.

5. In a. surveying instx'muent, e telescope rovided with e. vertical are, and u movable indeg, said are being graduated outwardly fium e zeropoint, near its middle und similerly on either side of said zero-point, Seid gruduations following a Certain law of net,- uml cosines, seid are having such selected anffulm' pusitiuns fz-omputed from Suid law as will give when placed on the iure, even wlmlonumber percentages whereby fur nn)- setting el' tbe telescope, can be reed by estimation, the percentage nlcorrectionIl to be subtracted from the el'JsL-.rved stadia distance, in ii-dvr tu obtain the true horizontal dis-inline.

WllJld/XM M. Bld/GIAN. Witnesses MARK M. lmmiicm, Mimet; E. THUMIDON. 

